EVERYONE knows that whales and (possibly) dolphins are smart. Sperm whales have the largest brains on the planet and, relative to body size, the brains of dolphins are second only to humans. But have they taken the next step and used this brainpower to pass important knowledge from generation to generation? That is, have they developed culture?

In The Cultural Lives of Whales and Dolphins, Hal Whitehead and Luke Rendell, two of the world’s leading cetacean biologists, make the case for cetacean culture. In fact, they suggest that for tens of millions of years – until the rise of modern humans – the most sophisticated cultures on Earth were those of whales.

“Until modern humans, the most sophisticated cultures on Earth were those of whales”

Asserting that any animal other than humans has culture is fraught with controversy, so Whitehead and Rendell spend a big chunk of their book defining the term “culture”&colon; essentially, information or behaviour acquired through social learning. This is important background, but most readers will find it dry and technical. Fortunately, we soon get to the whales, with plenty of biological detail setting out the evidence for whale culture.

In a few cases, this evidence seems indisputable&colon; humpback whales sing similar songs throughout entire ocean basins, and these songs change gradually during the lifespan of individuals. The only way that can happen is if individual whales listen to and learn from one another. Orca clans each have distinct calls that serve, essentially, as ethnic markers, even though the genetic differences between the clans are negligible. Sperm whales have vocal clans, too, that span whole ocean basins. Cultural learning must be involved. And there are a few cases, such as “tail-walking” in dolphins and a peculiar sort of feeding motion in humpback whales, where biologists have actually seen the behaviour spread between individuals.

More often, though, the case for culture is a little murkier. Take, for example, the dolphins in Shark Bay, Western Australia, who carry sponges on their snouts while bottom-feeding. This probably protects them from sharp-spined fish, but only a few family units within the bay do it. This looks a lot like culture passed down from mother to daughter, but it could also plausibly be the result of specific environmental conditions or of genetic endowments. It’s not easy for land-bound biologists to be sure.

It’s even harder to know how important culture has been in shaping the ecology, evolution and environment of whales and dolphins. But that doesn’t stop the authors speculating that culture may be why orcas and sperm whales are successful top predators, and the most geographically widespread animals on Earth, except for humans. And if culture is as important to whales as it appears, then conservationists will need to protect not just their genetic diversity but their cultural diversity as well.

All this speculation is underlain by a wealth of biological detail, all carefully annotated, making this book a valuable – and usually very readable – resource for anyone interested in cetacean behaviour.